Associated with direct seeding and non-till culture or farming, the irregularity of the ground surface becomes important as conditioning aspect for appropriate seeding work.
In this sense, the capacity of the machine to overcome this limitation in association with other no less critical limitations such as the consistency of the ground and crop residues, turn out to be relevant.
There are two critical aspects to be considered in seed distribution systems, the possibility of moving vertically in order to correctly go along the irregularities presented by the ground surface, and in parallel, the need to have sufficient load on the body or seeding unit to introduce seeds uniformly to the desired working depth on the ground.
In this sense, longer linking and joint means favor moving along the ground, but affect the geometry of the machine making it too long and wide for transportation and, on the other hand, hinder the transfer of loads to the distribution system or seeding units.
In direct seeding productive situations where there is little or no chance that the irregularities of the ground surface, mainly wheel tracks produced during harvest, will become even so that at the time of seeding, the ground profile has a more regular surface, the troublesome situation of variability in the load transferred is critical conditioning seeding uniformity and depth, and seed-ground contact.
Load transfer systems of the great majority of seeders are based on mechanical principles using springs as active means.
These systems pose the disadvantage that when the spring tension increases the load transferred is often too excessive for the agronomic needs of the work and when the spring is relaxed they tend to be sub-optimal. This variation in the load magnitudes constantly occurs because the seeding system goes on an uneven ground surface thus articulating the deformable parallelogram which makes the spring tighten and relax.
This variability not only affects the quality of the seeding work, but it also conditions the life cycle of the distribution system components that bear point loads implying important efforts.
There are various systems in the prior art intended to overcome this problem. Some of these systems present pneumatic or oil-pneumatic solutions, which are not widely spread due to their high cost, thereby making seeder machines considerably more expensive. There is currently no standard machine available in the national market that uses pneumatic or hydraulic devices for such purpose.
Some systems that attempt to solve these problems without the use of pneumatic or oil-pneumatic solutions are also known. Among these, for example, those disclosed in Patent Applications AR 050878 A1 and JP 2003-125611 A can be cited. The solutions provided by such documents are considerably complex, thereby making the product more expensive, and the maintenance and regulation thereof much more complicated.
Consequently, there is an unfulfilled need for improved load transfer systems in seed distribution systems in order to overcome the problems mentioned above, especially the great variability in the load transferred when moving, providing a device that does not use hydraulic or pneumatic systems and which in turn is simple and ease to maintain.